Induction furnace



June 10, 1930. B TJOFLAT 1,763,200

INDUCTION FURNACE Filed Sept. 13, 1928 INVENTOR Gem/dB. '770f/m.

/ ATTORNEY Patented June 10, 1930 UNITED STATES PATENT OFFICE GERALD B. TJ'OFLAT, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8!; MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA INDUCTION FURNACE Application filed September 13, 1928.

This invention relates to induction furnaces and particularly to induction coils thereof.

An object of this invention is to provide an artificially cooled induction coil thatshall be simple in construction, easily manufactured and easily installed.

Another object of the invention is to provide an artificially cooled induction coil hav- )0 ing an improved space factor as compared with other artificially cooled coils heretofore utilized for similar purposes.

And a still further ob ect of the invention is to rovide an artificially cooled induction coil or induction furnaces or other inductive apparatus that shall have a large current-carrying capacity and a low 1 R loss.

For a better understanding of the invention, reference may be had to the following description, taken in conjunction with the accompanying drawing in which Figure 1 is a top p an view of an induction furnace embodying the invention.

Fig. 2 is a front plan view of the same devlce.

Fig. 3 is a View, in section, taken on line III-III of Fig. 2, and

Fig. 4 is a schematic dia ram of the circuit connections of the in uction coil em- :0 bodied in the structure illustrated in Figs.

1 to 3, inclusive. I

In the drawings, an induction-coil assembly 1 is disposed about a crucible 2 in which metallic materials may be melted by electroma netic induction; that is, the metals are melte" by the heating eflect produced by an alternating electromagnetic field developed by the coil 1 when a source of alternating current is applied thereto.

The frequency of alternating current which may be applied to the coil 1 in order to obtain efficient heating by electromagnetic induction may be of any value; however, the coil construction illustrated is particularly adapted for melting by electromagnetic induction when alternating current of commercial or low frequency is applied.

The coil assembly 1 comprises a coil 3 of hollow section. through which a cooling fluid, 59 such as water, may be caused to circulate,

Serial No. 305,671.

the coil comprising a plurality of turns spaced from each other, and a plurality of coils 4i and 5 of solid section the respective turns of which are interposed between the turns of the hollow-conductor coil 3. 5 The coils 3, 4c and 5 are insulated from each other by strips 6 of suitable insulating material, such as mica.

The respective coils 3, 4- and 5 may be connected either in series-circuit relation or in parallel-circuit relation but, in the present embodiment of the invention, the coils are shown as connected in series by means of jumpers or connectors 7 and 8.

When the coils 3, i and 5 have been wound, as shown in Figs. 2 and 3, they may be so compressed together by any suitable means (not shown) that the respective turns of the coils are in good thermal communication with each other. 7

' The coils 4 and 5, shown as being solid and rectangular cross section, may be made of such dimensions that they will carry a maximum of current with a minimum 1 R loss. The coil 3 may be so shaped that two faces thereof are of substantially the same width as the conductors constituting the coils 4 and 5.

When an alternating current is passed through the coil assembly 1, the PR loss developed therein will be carried away or dissipated in water or other cooling medium which may be pumped through the hollow coil 3. As will be observed, the heat generated in the solid coils 4 and 5 will be con- 5 ducted through the strips 6 of insulating material to the turns of the hollow coil 3.

By employing a coil construction as illustrated in the drawing, the number of ampere turns per unit of axial length of coil may be 9 increased to a value heretofore unknown because of the fact that a maximum of current-carrying material which permits of artificial cooling maybe located within a limited amount of space. 96 While much of the heat energy developed in the coil assembly 1 is caused by PR loss in the coil, an appreciable amount of heat is transferred thereto from the charge being melted in the crucible 2. This heat must we also,be absorbed by the cooling fluid passin through the hollow coil 3.

ile the coil assembly 1, illustrated in the drawings, has particular utility in induction furnaces, it is to be understood that such coil may be employed in transformers or other devices that are utilized for transformin electric energy from one voltage to anot er by electromagnetic induction.

The circuit connection of the coil assembly 1 is illustrated schematically in Fig. 4. If the coil is connected to a supply of alternating-current power, the current will flow through the hollow coil 3, the jumper 8, the coil 4, the jumper 7 and the coil 5.

While, in the coil construction shown in the drawing, a plurality of coils that are of solid cross section have been interposed between a coil that is of hollow cross section, it is to be understood that the number of coils of solid section may be varied without departing from the spirit and the scope of the invention.

Since various modifications may be made in the device embodying the invention without departing from the spirit and the scope thereof, it is to be understood that only such limiations shall he placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:-

1. An induction-coil winding comprising a plurality of turns of electric-conducting material having a passageway extending longitudinally therethrough and a plurality of turns of electric-conducting material of solid section interposed between the turns having the passageway therein and in thermal communication therewith.

2. An induction-coil winding comprising a plurality of turns of electric-conducting material having a passageway extending longitudinally therethrough, and a plurality of turns of electric-conducting material of solid section located between the turns having the passageway therein, all of said turns of solid section being in heat-interchanging relation with the turns having the longitudinally extending passageway, the radial width of all of the turns being substantially the same.

3. A windin structure comprising an induction coil 07' electric-conducting material having a passageway extending longitudinally therethrough and a plurality of induction coils of electric-conducting material of solid section interposed between the turns of the coil having the longitudinally extending passageway and in heat-conducting relation thereto.

In testimony whereof, I have hereunto subscribed my name this 4th day of Septemher, 1928.

GERALD B. 'rJoFLAT. 

